The invention relates to aligning images of a projection system, such as a liquid crystal display (LCD) projection system, for example.
Referring to FIG. 1, a reflective liquid crystal display (LCD) projection system 5 typically includes an LCD display panel (LCD display panels 22, 24 and 26, as examples) for each primary color that is projected onto a screen 10. In this manner, for a red-green-blue (RGB) color space, the projection system 5 may include an LCD display panel 22 that is associated with the red color band, an LCD display panel 24 that is associated with the green color band and an LCD display panel 26 that is associated with the blue color band. Each of the LCD display panels 22, 24 and 26 modulates light from a light source 30 to form red, green and blue images, respectively, that add together to form a composite color image on the screen 10. To accomplish this, each LCD display panel 22, 24 or 26 receives electrical signals that indicate the corresponding modulated beam image to be formed.
More particularly, the projection system 5 may include abeam splitter 14 that directs a substantially collimated white beam 11 of light (provided by the light source 30) to optics that separate the white beam 11 into red 13, blue 17 and green 21 beams. In this manner, the white beam 11 may be directed to a red dichroic mirror 18 that reflects the red beam 13 toward the LCD display panel 22 that, in turn, modulates the red beam 13. The blue beam 17 passes through the red dichroic mirror 18 to a blue dichroic mirror 20 that reflects the blue beam 17 toward the LCD display panel 26 for modulation. The green beam 21 passes through the red 18 and blue 20 dichroic mirrors for modulation by the LCD display panel 24.
For reflective LCD display panels, each LCD display panel 22, 26 and 24 modulates the incident beams, and reflects the modulated beams 15, 19 and 23, respectively, so that the modulated beams 15, 19 and 23 return along the paths described above to the beam splitter 14. The beam splitter 14, in turn, directs the modulated beams 15, 19 and 23 through projection optics, such as a lens 12, to form modulated beam images that ideally overlap and combine to form the composite image on the screen 10.
However, for purposes of forming a correct composite image on the screen 10, the corresponding pixels of the modulated beam images may need to align with each other. For example, a pixel of the composite image at location (0,0) may be formed from the superposition of a pixel at location (0,0) of the modulated red beam image, a pixel at location (0,0) of the modulated green beam image and a pixel at location (0,0) of the modulated blue beam image. Without this alignment, the color of the pixel at location (0,0) may be incorrect, or the color may vary across the pixel.
At the time of manufacture of the system 5, the LCD display panels 22, 24 and 26 typically are mounted with sufficient accuracy to align the pixels of the modulated beam images. One way to accomplish this is to approximate the correct position of the LCD display panels 22, 24 and 26; temporarily mount the LCD display panels 22, 24 and 26; and thereafter use the LCD display panels 22, 24 and 26 to attempt to form a white rectangular composite image onto the screen 10 to test the alignment of the display panels 22, 24 and 26. Referring to FIG. 2, if the LCD display panels 22, 24 and 26 are not properly aligned, then the resultant red 40, green 42 and blue 44 modulated beam images do not align, an alignment problem that may be apparent throughout the entire composite image. However, when the LCD display panels 22, 24 and 26 are properly aligned, the modulated beam images align and are not detectable from the composite image, as depicted in FIG. 3.
Unfortunately, aligning the LCD display panels 22, 24 and 26 to cause beam convergence may require a high degree of accuracy in the assembly of the system 5. Furthermore, such factors as aging and thermal drift, may cause the LCD display panels 22, 24 and 26 to fall out of alignment during the lifetime of the system 5.
Thus, there is a continuing need to address one or more of the above-stated problems.
In one embodiment of the invention, a projection system includes a light source, a display panel and a first circuit. The light source is adapted to generate light, and the display panel includes pixels to, modulate at least a portion of the light to produce a modulated beam image. The pixels are formed from groups of subpixel cells, and the display panel is adapted to reorganize the groups to shift positions of the pixels. The first circuit is coupled to the display panel to selectively cause the display panel to reorganize the groups.
In another embodiment, a method includes modulating beams of light with display panels to form a first modulated beam image and a second modulated beam image. The display panel includes display pixels, and the display pixels are associated with image pixels of the first and second modulated beam images. Without moving any of the display panels, the positions of some of the display pixels are changed to move the first modulated beam image with respect to the second modulated beam image.
In another embodiment, a method includes generating light and using pixels to modulate at least a portion of the light to produce a modulated beam image. At least two subpixel cells are grouped together to form each display pixel. The grouping of the subpixel cells is changed to shift positions of the display pixels.
In yet another embodiment, a display panel includes subpixel cells and a switch circuit. The switch circuit is adapted to form display pixels by grouping the subpixel cells and change the grouping of the subpixel cells to shift positions of the pixels.